Jessie J sang a duet of 'Price Tag' with a lucky fan at her a MasterCard 'Priceless Gig' last Friday (14.09.12)

The pop star performed for just 400 competition winners at the Under The Bridge music venue in London for a MasterCard 'Priceless Gig' on Friday night (14.09.12).

The evening was extra special for 23-year-old Samantha Neal who was the winner of MasterCard's Priceless Duets competition, which invited fans to submit an audition video to win the once-in-a-lifetime opportunity to perform with their music idol.

Samantha sang 'Price Tag' with Jessie and admitted afterwards she would never forget the incredible experience.

She said: "I feel unbelievably lucky to have had the chance not only to meet Jessie J but also to perform with her in front of 400 people. It was an absolutely incredible experience, made even better by how inspirational Jessie is - I'm so grateful to her and MasterCard for this experience."

Jessie wowed the crowd - who won their tickets by entering their details at at pricelesslondon.co.uk - with a hit-filled set backed by a full band and an incredible lights show.

Highlights included 'Nobody's Perfect' and 'Do It Like A Dude' which had all of her fans dancing.

At one point, Jessie urged all her fans to stop filming the show on their phones and cameras and "have a moment for us".

The 24-year-old singer ended her set with a stunning rendition with 'Domino'.